Brake drum



Jan. 2, 1945.

` c. HOLLERITH BRAKE DRUM riled April 24, 1941 CHARLES HULLERITH Patented Jan. 2, 1945 2,366,262 `B Rlum DRUM- i Charles Holleritln .Iackson, Michl, assignery to` "Hayesllndu'stries, Inc., Jackson; Mich., a corporation'I of Michigan I @Application anni 2l, 19411,.seriaiNmsamo/is;

`5ff`11aims. (cl. 18s-21s) i i The presentfvinvention,relates.togimprovernents inwbrake i vdrum .construction having particular reference f to :brake` drumsy having anr outer reine. forcing shell of a material'. lofl high: tensile strength;as .i for fexample, .l steel, Y andan inner wearingliner of aima-terialofj `a lower modulus `offelasticity; as;i'ortexample;` cast iron.` Goin-` .positey drums-ofl thisftype of construction .i are` lof lighter weight and less.'` expensive to l fabricate lthan` drumsentirely fabricated.- from; east-l iron,

`especiallytwllerethe\composite .drum is of a cenl trifugal.casticonstruction.` i i Imthe` manufactureof centrifugal cast `brake drums-,fthe` outerfshell of the drum maybe `'formed by'` rolling `strip sheet: metal stock .into =a anged circular `rim Withfthe opposite i ends butt `welded.`

.This irixnfis 'then rotated i at high speed and the castnmeta-lwilows intoithe rim fand isdistribut-ed by centrifugal actiorr toll form an i integral;` liner withmhe rim.` Inithefmanufactureof brakes :for automobiles ,and airplanes, it hasibeen -thefpractice, in ordento prov-idethepouter.shelbwitha torque `flange ci adequate;A strength; tof roll the shell from l/a'f-s.' stocke with the-"cast: lineron theorderoffS/ief tol/1." in thickness; i

. .AhF the `rate at` whichbrakes` areapplied to bring. automobilesi `and` airplanes` from operating andflani'iing; Speeds xtota full stop, "extremely high i: surfaceV temperatures are instantly gener.- ated,alongztheinnertwearingsurfacesof"thebrake drum. `This-,high differential ,in temperatures betweenitheinnerJ and outer 'surfaces-.oi thefdrum upon` i repeated rstops, in. the f case r of; heavytbrake drums ,fabricated V entirely l of :cast iron,` causesvthe` same to become.` out of c' round; and/.oreshrink` in diameterzi `Reductionv.iniinner diameter of the brake drum from .020" to .080 upon as few as 100 stops have been experienced. With relatively thin steel drums reduction in diameter in the order of .080 have been noted in as few as two` of a construction which will not become warped or out of round or shrink to an objectionable` degree under extended use.

Another object is to provide a brake drumhaving outer and inner structure of ymaterial of substantially different moduli of elasticity in which the, ratio of `thiclniesses of l thefdifierent-material is; approximately:inigthe1reversetratio: of their moduli oftelasticity..

`Another object is-toprovideafbralnldrurnhav-- ing, an outerpshell, and? anoastfircnjnner liner in `which. the `thick-ness.` of the` steel shelltbackf ingslip the castiironlliner hasnbeenfreducedover.

standard `practices to iarfpo'nt eliminating to -1 an objectionable y i extent warping.` and... thel developv mentofout oiroundlcenditions aswell asfsl'lrinkf` i age in service.. g l i A further, object isqto4 provide .a;composi.te steel andcastliron idrum'in .whichlthe tthickness:of, the steeLis.:app;roximately%thesthicknessrofathacast iron.l i i u Aistill-further.objetlisi-totprovidega centrifugal cast brake idrumiworkablamk.withiaasurface provi sionufor'facilitatingy thegmachining: ofpithe idrurn to fbringthe materialiof, different ,moduli i of elas ticity` into fthei-r preferred thickness lratiofwvlhile providinguaxtorque;dlange l;of;ade1;u1ate strength.

These Y andi other objects :and advantages,res-id ing in ,theA i combina-tiem arrangement ,1 and fr con-` struction `ofr thepantsf will Eber'V apparent-ifrom .fthe

following specicationeandf-annexed claimsiwhen taken with the accompanyingidrawing in-which Eig: 1 is aa fragmentary Wcross-sectional View fof av work blank offa centrifugahbrakedrumlbefore division, i

.Fig; 2lis asimilar view-otafbraketdrumlafter `Having reference f. to r the r accompanying` draw-ling, in Figi, `1- istshown: a .'fragmentarynseetion through an, annular riqnlllshaving flangesu lf2. and

`I {l1-.to l confine ythecasttmetal inner` liner:` `I Bi `em.-` braced by the outer shell portion I8. By splitting the rim I0 along the vertical line a-a two similar centrifugal cast brake drums 20 result as shown machined in Fig. 2.

The drum 20 as shown in Fig. 2 comprises a torque Iiange 22 and an outer shell 24 of integral construction and preferably fabricated from a sheet material of relatively high tensile strength, as for example, steel. `The `shell 24 embraces an inner liner 2B presenting a wearing surface.` The material making up the liner 26 will usually be of a lower modulus of elasticity than that of the shell 20, as for example, cast iron. I have found that by reducing the thickness of the shell 2l)` over standard practice, that repeated stops, instantly heating the surface 28 to high temperatures, will no longer result in the development of objectionable warping and out of round conditions or shrinkage of the brake drum. In one test ran upon a 12 drum in which the shell 2|] was of steel in the order of thick and the liner 26 of cast iron in the order of 11716" thick along the major portion of its width, the out of round condition which developed upon 175 stops was in the order of .003" to .004". Witha similar drum having a shell ,20 in the order ofl 1/8 thick which wuld'correspond to standard practice, 20 stops produce an out of round condition in the order of .020. With the thinner outer shell, upon 100 stops, no apprecif able reduction in diameter was experienced as compared with a reduction*A in diameter in the order of .020I to .030" with another shell-oi standard thickness. 'y

The tests that have been run wouldappear'to indicate that the ratio of the 'thicknesses' 'of-ref inforcing shell 2U and the liner 26 should, beiny the reverse order of their moduli of elasticity. For example, in the'case of steel and cast iron 'in which E is approximately 30,000,000 and 10,000;- 000, respectively, if the castiron lineruis' agg" thick, the shell 20 shouldbe in the order of '1167 thick. It should be understood that the reference to steel and cast iron is by way of` example only as the principles of the present development have equal application to other -suitable metals and alloys. aluminum bronze or other suitable wearingmaterial of a low modulus of elasticity, l

' In practice there is an advantage in rolling the shell20 from stockof uniform thickness,wlth the thickness determined by the required strength of the torque ange 22. When such a practiceis carried out in connection with the present invention it necessitates machining the shell 20 to the proper thickness i'n cases where the thickness of thestorque ange will exceed the desiredthickness of the shell 20. In Fig. 1 the dotted-line 3U `represents the amount of metalv that Vis to be removed from the shell 20 Ain order tov obtain the desired ratio of thicknesses between the shell 20 and liner 26. To facilitate the machining of the shell v2llto the desired thickness, the edge portions 32` are rolled with steps 34 of a depth corresponding to the amount'of metal that is to be removedfrom the web" of the drum.`Wi`th this arrangement, at the time the drum is chucked in alathe tobe turned, the operator cangauge his depth of cut from the surface portion 3 2. ",Fig. 2 shows the drum `with the, shell 2|) machined downto the dotted line` l3l) of Fig. 1. As shown, the torquefilange 22 is approximately twice the thickness of the shell 20 as" machined. The forml of the invention illustrated inFig. 3 is without any arrangement for facilitating the For example, the liner 26 couldV be of machining of the shell 20 to the desired thickness, the stepped portion 32 having been eliminated.

Obw'ously, many methods of securing the desired thickness of material in the torque flange I 22 and shell 20 will occur to those skilled in the art. For this reason, I do not wish to be limited to any specific manner for carrying out the prinv `shell and an inner wearing liner of different ma- ,'terial, the ratio of thicknesses of said shell and liner to each @other approximating the reverse ratio of thelrmoduli of elasticity.

2. A `brake drum having an outer reinforcing sheet metal shell and an inner cast metal Wearing liner, the "ratio of thicknesses of said shell and liner tol each other' approximating the reverse ratio of their respective moduli of elasticity.

3; A brake drum having an outer reinforcing sheet metal shell and an inner cast metal wearing liner, the ratio of thickness of said shell and liner to each other being in the order of`1to3 and approximating the reversed ratio of `their respective moduli of elasticity. f

'4.A brake drum having an outer reinforcing steel shell and an inner cast iron liner, the steel shell being in the order of 1/3 or less-the thickness of the cast. iron liner, with the cross-sectional proportions of the steel shell and cast iron linei,` being such Vthat the steel will have sufficient strength to reinforce and support the ca st iron liner in use, yet the steel shell shall have insufficient tensile strength to resist expansion of the castiron liner to an extent which would produce failure i'n compression of said liner, whereby Warpage and shrinkage following repeated brake application is substantially obviated. 5. A centrifugal cast brake drum having a rela.- tively thin outer steel reinforcing shell and a, relatively thick inner wearing liner of cast iron, the i major-embracing portion of saidouter shell being in the order of 1A; or less of the thickness of the liner, with the cross-sectional proportions of the i shell and liner being such that the shellhas sul# cient tensile strength to`reinforce the liner in 

